Wharfage

Figure 10-28.-Two types of tie-rod anchorages for bulkheads. of the tie rods are anchored by means of a channel wale. In the figure, the construction sequence begins when the shore and bottom are first excavated to the level of the long, sloping dotted line. The sheet piles for the bulkhead and the anchorage are then driven. The supporting piles for the tie rods are driven next, after which the tie rods between the bulk and the anchorage are set in place and the wales are bolted on. The tie rods are prestressed lightly and uniformly, and the backfilling then begins. The first backfilling operation consists of placing fill over the anchorage, out to the dotted line shown in the plan. The turnbuckles on the tie rods are then set to bring the bulkhead plumb, and the rest of the backfill is worked out to the bulkhead. After the backfilling is completed, the bottom outside the bulkhead is dredged to the desired depth. WHARFAGE As mentioned earlier, wharfage structures allow vessels to lie alongside for loading or unloading. Moles and jetties are the most typical forms. Figure 10-29.-Working drawings for a steel sheet pile bulkhead. Moles and Jetties A mole is simply a breakwater that serves as a wharfage structure. The only difference is that its inner or harbor face must be vertical and its top must function as a deck. In a similar way, jetties also serve as wharfage structures. BELOW THE WATER TABLE When construction is carried on below the groundwater level, or when underwater structures like seawalls, bridge piers, and the like, are erected, it is usually necessary to temporarily keep the water out of the construction area. This is typically done with well points, cofferdams, or caissons. Well Points Well points are long pipes thrust into the ground down to the level at which the water must be excluded. 10-15